1. Field of the Invention
The present invention relates to the field of mobile networking and more particularly to mobile networking in a multi-nodal network environment.
2. Description of the Related Art
With the advent of ubiquitous computing, a sheer number of electronic devices are capable of communicating through wireless technologies by using their Internet protocol (IP) addresses. Mobile IP version 6 (v6) is a protocol referred to as Mobile IPv6 that specifies the redirection of traffic between a mobile node disposed in a mobile device and other correspondent nodes throughout the network from one address to another in order to provide transparent Internet connectivity while a mobile device is moving. In this regard, the signaling for such redirection of traffic is done between the mobile and correspondent nodes.
In Mobile IPv6, a mobile node can be assigned two network addresses. The first assigned address is a home address allocated to the mobile node when the mobile node is at home network. The second assigned address is a care-of address allocated to the mobile node when the mobile node becomes attached to foreign network. Whenever the mobile node is assigned to a new care-of-address, the mobile node sends an update message to its home agent. The update message contains information pertaining to the current point of attachment for the mobile node. Therefore, when the home agent intercepts a packet toward the mobile node, the home agent encapsulates and redirects the packet to the current location of the mobile node.
Any node communicating with a mobile node is referred to as a “correspondent node”. There are two known modes of communication between a mobile node and a correspondent node. The first mode, referred to as a bidirectional tunneling mode, does not require Mobile IPv6 support from the correspondent node. Rather, in the bidirectional tunneling mode, packets sent from the correspondent node are routed to the home agent and then tunneled by the home agent to the mobile node. Conversely, packets sent from the mobile node are tunneled to the home agent and then routed normally from the home network to the correspondent node.
The second mode, a route optimization mode, requires the mobile node to register a binding at the correspondent node. Thereafter, packets from the correspondent node can be routed directly to the care-of address of the mobile node. Likewise, packets sent from the mobile node are sent directly to the correspondent node. In this way, by routing packets directly to the care-of address of the mobile node, a shortest communications path is used, and congestion at the home agent and home link of the mobile node can be avoided.
Essential to route optimization is the successful binding on behalf of the correspondent node of the care-of-address for the mobile device. Request for Comment (RFC) 3775 in particular describes the process performed by a mobile node in registering its current location—namely its current care-of address—with any correspondent node with which the mobile node communicates. Generally, the binding process requires the use of binding update messages to register a binding between a home address of a mobile device and a current care-of address of the mobile device with those correspondent nodes with which the mobile device communicates.
Before a mobile node may send a binding update message, however, the mobile node first must complete a return routability procedure. The return routability procedure allows the correspondent node to determine, within reason, that the mobile node is addressable at both its home address as well as its care-of address. Only with this assurance is the correspondent node able to accept binding update messages from the mobile node. The return routability procedure is performed by testing whether packets addressed to the two claimed addresses are routed to the mobile node. The mobile node can pass the test only if it is able to supply proof that it received certain data which the correspondent node sends to those addresses.
Specifically, in a return routability procedure, each correspondent node keeps a secret key known as a keygen token and generates a nonce at regular intervals. The correspondent node uses the same secret key and nonce with each mobile node in communication with the correspondent node so that the correspondent node need not generate and store a new nonce for each new mobile node contacting the correspondent node. Each nonce can be identified by a nonce index. When a new nonce is generated, the new nonce is associated with a new nonce index. Resultant message exchanges are sent with an IPv6 “Mobility Header” in IPv6 packets.
Notably, the procedures outlined in RFC 3775 are sufficient for a single-node case, where the correspondent node “owns” all IP addresses assigned to the node. Yet, the procedures outlined in RFC 3777 fail to address a data center environment where in a sysplex any one of a number of target nodes share the same IP address and there is some form of load balancer that selects the particular target node for each new connection.